Source: Medicines and Medical Devices Safety Authority (NZ) Revision Year: 2022 Publisher: Viatris Ltd, PO Box 11-183, Ellerslie, AUCKLAND www.viatris.co.nz Telephone 0800 168 169
For the treatment of supraventricular extrasystoles and supraventricular tachycardias, and in WolffParkinson-White (WPW) syndrome. Also for the treatment of life-threatening documented ventricular tachyarrhythmia.
The use of Rytmonorm is not recommended in patients with less severe ventricular arrhythmias, even if the patients are symptomatic. Because of the proarrhythmic effects of Rytmonorm, its use should be reserved for patients in whom, in the opinion of the physician, the potential benefits of treatment outweigh the risks.
The use of Rytmonorm should be initiated by a specialist physician. The individual maintenance dose should be determined under cardiological surveillance including repeated ECG monitoring and repeated blood pressure control (titration phase). If the QRS interval is widened by more than 20%, the corrected QT interval is lengthened or second or third degree AV block occurs, the dose should be reduced or discontinued until the ECG returns to normal.
The dosage is to be adjusted to the individual patient’s requirements.
It is essential that each patient given Rytmonorm be evaluated electrocardiographically and clinically prior to and during therapy to determine whether the response to Rytmonorm supports continued treatment.
For initial and maintenance treatment a daily dose of 450 to 600 mg (1 film-coated tablet of Rytmonorm 150 mg 3 times daily or up to 2 film coated tablets of Rytmonorm 150 mg twice daily) is recommended.
Occasionally an increase of the daily dose to 900 mg may be necessary (2 film-coated tablets of Rytmonorm 150 mg 3 times a day). This daily dose should be exceeded only in exceptional cases and under strict cardiological control. This data applies to patients with a body weight of about 70 kg. The daily doses are to be reduced accordingly for patients weighing less (e.g. two thirds of the dosage in patients with a body weight of approximately 50 kg). Dose increases should not be attempted until the patient has been receiving treatment for three to four days.
The safety and efficacy of Rytmonorm in children has not been established.
No overall differences in safety or effectiveness were observed in the geriatric patient population, but greater sensitivity of some older individuals cannot be ruled out, therefore, these patients should be carefully monitored. The same applies to maintenance therapy.
During the initial phase of treatment in the elderly or in patients with myocardial damage the dose of Rytmonorm should, as with other anti-arrhythmic agents, be increased gradually and with special care. Any dose increases that may be required should not be undertaken until after five to eight days of therapy.
In patients whose liver and/or kidney function is impaired, there may be drug accumulation after standard therapeutic doses. Nonetheless, patients with these conditions can still be titrated on propafenone hydrochloride under ECG and clinical monitoring. The dose of propafenone given to patients with impaired hepatic function should be approximately 20 to 30% of the dose given to patients with normal hepatic function.
Because of their bitter taste and surface anaesthetic action, the tablets should be swallowed whole with some liquid.
The effects of propafenone hydrochloride overdose in the myocardium manifest as impulse generation and conduction disorders such as PQ prolongation, QRS widening, suppression of sinus node automaticity, AV block, ventricular tachycardia, ventricular flutter, ventricular fibrillation and cardiac arrest. Reduction of contractility (negative inotropic effect) can cause hypotension which, in severe cases, can lead to cardiovascular shock.
Metabolic acidosis, headache, dizziness, blurred vision, paraesthesia, tremor, nausea, constipation, dry mouth and convulsions have been reported on overdose.
Death has also been reported.
In severe cases of poisoning, tonic-clonic convulsions, paraesthesia, somnolence, coma and respiratory arrest may occur.
In addition to general emergency measures, the patient’s vital parameters should be monitored in an intensive care setting, and rectified, as appropriate.
Defibrillation as well as infusion of dopamine and isoproterenol have been effective in controlling rhythm and blood pressure. Convulsions have been alleviated with intravenous diazepam.
General supportive measures such as mechanical respiratory assistance and external cardiac massage may be necessary.
Owing to high protein binding (> 95%) and the large volume of distribution, haemodialysis is ineffective and attempts to achieve elimination via haemoperfusion are of limited efficacy.
General supportive measures and medication for symptomatic treatment as defined in treatment guidances may be necessary.
For further advice on management of overdose please contact the National Poisons Information Centre (0800 POISON or 0800 764 766).
Rytmonorm 150 mg: 3 years.
Store at or below 25°C.
Blister packs. Pack size of 50 tablets.
Not applicable.
© All content on this website, including data entry, data processing, decision support tools, "RxReasoner" logo and graphics, is the intellectual property of RxReasoner and is protected by copyright laws. Unauthorized reproduction or distribution of any part of this content without explicit written permission from RxReasoner is strictly prohibited. Any third-party content used on this site is acknowledged and utilized under fair use principles.
